Directional crack propagation and optimization strategies for multi-hole shaped charge blasting in tunnel construction

In tunnel construction, traditional blasting techniques frequently trigger over-under excavation and damage to surrounding rocks, thus affecting the safety and efficiency of project. Multi-hole shaped charge blasting can effectively address these issues, yet its action mechanism and improved method remain unclear. To bridge this gap, this study validates the reliability of numerical calculation in LS-DYNA through model tests. Then the numerical models for multi-hole shaped charge and traditional blasting are developed, focusing on the stress wave propagation and crack development under both methods. After combining the real-world project with the simulation results, to decrease the amount of blast holes applied in blasting, the layout design of the blasthole distance and diameter are produced and investigated numerically. Findings indicate that shaped charge blasting effectively prevents over-under excavation by achieving directional penetrating cracks. Multi-hole shaped charge blasting technology after optimization can increase the distance between the blasting holes, greatly reducing the damage and disturbance to the retained rock mass, which is conducive to the later support and long-term stability of the tunnel surrounding rock.